Aristocracy, oligarchy, monarchy, and democracy are old concepts of government which can be traced back to Ancient Greece.

Aristocracy is "rule by the best," and the concept comes from Plato's Republic. Plato argued for an aristocracy of philosopher kings. He thought that philosophers were ideally suited to political leadership. Historically, aristocracies have been based on wealth or land ownership. But other criteria have been used throughout the ages.

Monarchies have often flourished alongside aristocracies. Both have been the targets of revolutionaries, as in eighteenth-century France. Monarchies are ruled by a king or queen. Throughout most of history, the monarchs' powers were absolute. Today, most are constitutional monarchs, and they serve as symbols of the state with few real powers. However, Saudi Arabia is an example of a country where the king still holds great power.

Democracy is "rule by the people" themselves or through their representatives. Today, this is the dominant form of government in the West. However, many believe that their representatives do not always act in the interests of the people they represent. For instance, in the United States, elected representatives often pass legislation that overwhelmingly benefits the affluent classes or corporations. Another problem with modern-day democracy is low voter turnout.

Oligarchy is "rule by the few," and that often means the rich. Many people believe that the United States is now an oligarchy rather than a democracy. Billionaires donate huge sums to candidates and are usually rewarded by the passage of favorable legislation. One way to combat this problem is by public financing of election campaigns.

Here are the definitions of each type of government:

• An oligarchy is a style of government in which only a few people have any power. Often, these are wealthy individuals who use their power and influence to further enhance their financial status.  
• An aristocracy is another type of government in which power and influence are held by a minority of people. Unlike an oligarchy, however, aristocrats derive their power from their family lineage. They often have hereditary titles, for example, like duke or earl, and their families have held power for generations.
• A monarchy is a type of government in which there is only one ruler and that is a king or a queen (a monarch). Like an aristocrat, a monarch inherits his or her title. In an absolute monarchy, the monarch exercises total control over all aspects of the government. In contrast, in a constitutional monarchy, like in the United Kingdom, the monarch's powers are curtailed and moderated by the government.
• A democracy is a type of government in which power is held by the people. To exercise this power, many democracies use a system of voting in which the people choose a number of elected representatives to serve in government.

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Your class has studied four kinds of government.  They were oligarchy, aristocracy, monarchy, and democracy.  Monarchy and democracy are easy to distinguish from one another.  Monarchy is rule by one person.  In a monarchy, a king or a queen rules and that person has all the power.  In Greece, there were only kings and no queens.  In a democracy, the people rule.  In Greece, this meant that the adult free males ruled.  These free adult men got to assemble and vote on proposed laws.  They were the ultimate source of authority. 

Oligarchy and aristocracy are less distinct from one another.  Both of these can be defined as rule of the few.  However, there is a difference in how “the few” are selected.  In an aristocracy, the few are selected on the basis of their family ties.  People of a given few families have the right to be part of the few.  In an oligarchy, the selection is generally on the basis of power or wealth.  The people who get to rule are at least people who have, in some way, proven that they deserve to rule.  Thus, these are similar, but not identical types of government.